modpost: merge two similar section mismatch warnings

In case of section mismatch, modpost shows slightly different messages.

For extable section mismatch:

 "%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n"

For the other cases:

 "%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n"

They are similar. Merge them.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>